Volume 2, Issue 1

Proteins are considered to be the key players in structure, function, and metabolic regulation of our bodies. The mechanisms used in conventional therapies often rely on inhibition of proteins with small molecules, but another promising method to treat disease is by targeting the corresponding mRNAs. In 1998, Craig Mellow and Andrew Fire discovered dsRNA-mediated gene silencing via RNA interference or RNAi. This discovery introduced almost unlimited possibilities for new gene silencing methods, thus opening new doors to clinical medicine. RNAi is a biological process that inhibits gene expression by targeting the mRNA. RNAi-based therapeutics have several potential advantages (i) a priori ability to target any gene, (ii) relatively simple design process, (iii) sitespecificity, (iv) potency, and (v) a potentially safe and selective knockdown of the targeted cells. However, the problem lies within the formulation and delivery of RNAi therapeutics including rapid excretion, instability in the bloodstream, poor cellular uptake, and inefficient intracellular release. In an attempt to solve these issues, different types of RNAi therapeutic delivery strategies including multifunctional RNA nanoparticles are being developed. In this mini-review, we will briefly describe some of the current approaches.

Molecular computers have existed on our planet for more than 3.5 billion years. Molecular computing devices, composed of biological substances such as nucleic acids, are responsible for the logical processing of a variety of inputs, creating viable outputs that are key components of the cellular machinery of all living organisms. We have begun to adopt some of the structural and functional knowledge of the cellular apparatus in order to fabricate nucleic-acid-based molecular computers in vitro and in vivo. Nucleic acid computing is directly dependent on advances in DNA and RNA nanotechnology. The field is still emerging and a number of challenges persist. Perhaps the most salient among these is how to translate a variety of nucleic-acid-based logic gates, developed by numerous research laboratories, into the realm of silicon-based computing. This mini-review provides some basic information on the advances in nucleic-acid-based computing and its potential to serve as an alternative that can revolutionize silicon-based technology.

A novel RNA motif was identified based on its sequence by computational structure modeling. The RNA molecule was reported to be a substrate for the structurally specific endoribonuclease, Dicer, which cleaves doublestranded RNA and cuts out 20−25 nucleotide fragments. This enzymatic property was essential for the potential utilization of the motif in the nanoparticle design of further biological experiments. Herein, the protocol for the prediction of the structure of this motif in-silico is presented, starting from its primary sequence and proceeding through secondary and tertiary structure predictions. Applying RNA architectonics, this novel structural motif, 3wj-nRA, was used for rational RNA nanoparticle design. The molecules, which are based on this three-way junction fold, may assemble into more complex, triangular shaped nano-objects. This trimeric nanoparticle containing 3wj-nRA motif can be further utilized for functionalization and application.

Targeted delivery of bioactive compounds is a key part of successful therapies. In this context, nucleic acid and protein-based aptamers have been shown to bind therapeutically relevant targets including receptors. In the last decade, nucleic acid-based therapeutics coupled to aptamers have emerged as a viable strategy for cell specific delivery. Additionally, recent developments in nucleic acid nanotechnology offer an abundance of possibilities to rationally design aptamer targeted RNA or DNA nanoparticles involving combinatorial use of various intrinsic functionalities. Although a host of issues including stability, safety and intracellular trafficking remain to be addressed, aptamers as simple functional chimeras or as parts of multifunctional self-assembled RNA/DNA nanostructures hold great potential for clinical applications.

Nucleic acid nanotechnology offers many methods to build self-assembled structures using RNA and DNA. These scaffolds are valuable in multiple applications, such as sensing, drug delivery and nanofabrication. Although RNA and DNA are similar molecules, they also have unique chemical and structural properties. RNA is generally less stable than DNA, but it folds into a variety of tertiary motifs that can be used to produce complex and functional nanostructures. Another advantage of using RNA over DNA is its ability to be encoded into genes and to be expressed in vivo. Here we review existing approaches for the self-assembly of RNA and DNA nanostructures and specifically methods to assemble large RNA structures. We describe de novo design approaches used in DNA nanotechnology that can be ported to RNA. Lastly, we discuss some of the challenges yet to be solved to build micron-scale, multi stranded RNA scaffolds.